The invention relates to a ball joint, in particular, to a ball joint for head lamp adjusting devices of motor vehicles. Prior art discloses a ball joint for use in head lamp adjusting devices of motor vehicles and comprising a ball stud having a shank with a ball at one end thereof and a ball socket having resilient arms with outer surfaces corresponding to the outer surface of the ball and engaging the same. In this prior art ball joint, a retaining ring is pushed over the resilient arms to prevent expansion of the arms and thereby inadvertent displacement of the ball stud out of the socket. Using such a retaining ring increases costs of production of ball joints.